250 CONTROL OF FLIES 



require lartje quantities of fluid, and usually seek something to 

 drink early in the morning. A method which has often proved 

 very successful, based on this fact, has been described by 

 Hermes (191 1). 



Formalin, which, as purchased from the chemist, contains 

 about 40^0 of formaldehyde in solution, is diluted b)^ the 

 addition of water to contain about 2 "/o of formaldehyde, and the 

 solution placed in saucers or shallow dishes on window sills or 

 tables. During the day, in dining rooms, kitchens and other 

 places, where there is plenty of fluid material for food and drink, 

 many of the flies cannot be expected to drink the formalin 

 solution, but if all other fluids are removed or covered up in the 

 evening, the flies, which do not seem to object to the presence 

 of the formalin, will greedily drink the solution in the morning. 

 After doing so they usually die within a short distance of the 

 vessel. This solution has the advantage of being non-poisonous 

 to man, and may therefore be used with impunity around food. 



Howard (191 1, p. 184) records another simple method 

 described in the Journal of the Department of Agriculture of 

 Western Australia. " Flies may be effectively destroyed by 

 putting half a spoonful of black pepper in powder on a tea- 

 spoonful of brown sugar and one teaspoonful of cream. Mix all 

 together and place in a room where flies are troublesome, and it is 

 said they will soon disappear." 



Fumes created by burning pyrethrum powder and other 

 substances have been recommended to stupefy flies, but could 

 scarcely be used in sufficient concentration in living rooms. 

 According to Hermes (191 1, p. 540), "the fly-fighting committee 

 of the American Civic Association recommends the following : 

 Heat a shovel, or any similar article, and drop thereon twenty 

 drops of carbolic acid ; the vapour kills flies." In many places 

 this method might be employed with advantage. 



Food, especially substances, such as milk, condensed milk, 

 sweets and fruit, which are consumed without cooking, should, 

 when not in use, be protected against visits from flies. In many 

 of these articles of food bacteria deposited by the fly multiply 

 rapidly especially during warm weather, so that the initial dose 

 deposited by the fly may be multiplied many times in the hours 



